<?php
$db=new PDO('mysql:host=localhost',"root",'12qwas');
$r=$db->exec('create database if not exists db3');
$r=$db->exec('use db3');
$r=$db->exec('create table if not exists students(xh varchar(9) primary key, name varchar(50),age int default 0)');
$r=$db->exec("delete from students where xh='233110203'");
var_dump($r);
$db->exec('truncate table students');
$r=$db->exec("insert into students(xh,name,age) values('233110201','程1',18),('233110202','程2',19),('233110203','程3',19)");
var_dump($r);
$r=$db->exec("update students set name='程6' where xh='233110201'");

var_dump($r);